Tampons are designed to contain a particular amount of menstrual fluid. The amount of menstrual fluid absorbed by a tampon can vary depending on absorbency levels. For example, in the United States, tampon absorbency can range from less than 6 grams (Junior absorbency) grams to 15–18 grams (Ultra absorbency). In order to ascertain whether a tampon has reached its absorbent capacity, the tampon must be removed and viewed, resulting in the destruction of the tampon, as most women are reluctant to reinsert the tampon. In most cases, a user will remove a tampon before it has reached its absorbent capacity in order to prevent an accident wherein the absorbent capacity of the tampon is exceeded. Once the absorbent capacity is exceeded, the excess menses flows unimpeded from the vagina to soil the user's clothing.
A determinative criteria frequently used to gauge tampon replacement is the amount of time elapsed since insertion. The time elapsed criteria for changing tampons is not satisfactory for several reasons, e.g., the menstrual flow rate varies throughout the menstruating period and much adsorbent capacity of tampons is wasted due to the tendency to change before an accident occurs.
The flow variation throughout the period causes problems as to how long to wear a tampon because a user cannot establish a definite time period for which the absorbent capacity within a tampon is sufficient. Therefore, she is in a quandary as to how long to wear specific tampons during days of heavy flow as contrasted to days of light flow.
A correlation between tampon performance during light flow versus heavy flow is difficult for the user to make. Thus, since the user would rather be safe than sorry, she frequently removes a tampon before the absorbent capacity of the tampon has been reached and wastes much of the product she had purchased.
Tampons have been made larger and with different materials to obtain higher absorbencies, often resulting in product claims that a user would not have to change the tampon as often. But the user would still waste a portion of the tampon absorbent capacity, as most users are not willing to risk having an accident. Therefore, bigger tampons provide a longer wearing time but do not approach the problem of fully using the absorbent capacity within a tampon. In rare cases, should a user leave the tampon in for an extended period of time, a life threatening infection may develop.
Wearing a high absorbency tampon can lead to discomfort and other problems as well. Women will sometimes wear a larger absorbency tampon due to the fear of tampon failure, especially if she is uncertain how often she will be able to access privacy in order to change the tampon. If the tampon is unsaturated, there may be drying of the vaginal wall, which may cause discomfort upon the tampon's removal.
Thus, there is a need for a tampon wetness detection system that signals the user to change the tampon prior to soiling the user's clothing.